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United States Patent |
5,779,433
|
Bocchi
|
July 14, 1998
|
Rotary suction and blowing machine
Abstract
The invention relates to an improved suction and blowing machine comprising
an impeller provided with blades which rotate internally of an annular
channel afforded in a body. The annular channel comprises a first tract
having a transversal section which is greater than that of the blades, and
is constituted by two communicating semichannels. The annular channel
extends from an intake mouth to a delivery mouth and is provided with a
peripheral wall facing external peripheral edges of the blades which
peripheral wall bears a cusp-section projecting element extending over an
entire length of the first tract of the peripheral wall and creates
thereon two concave surfaces.
Inventors:
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Bocchi; Giuseppe (Parma, IT)
|
Assignee:
|
ESAM S.P.A. (Parma, IT)
|
Appl. No.:
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778364 |
Filed:
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January 2, 1997 |
Foreign Application Priority Data
Current U.S. Class: |
415/55.1 |
Intern'l Class: |
F04D 029/42 |
Field of Search: |
415/55.1-55.6
|
References Cited
Foreign Patent Documents |
0351372 | Jan., 1990 | EP.
| |
459269 | Dec., 1991 | EP.
| |
567874 | Nov., 1993 | EP.
| |
872819 | Apr., 1953 | DE.
| |
1956013 | Nov., 1969 | DE.
| |
2131952 | Jan., 1973 | DE | 415/55.
|
206795 | Feb., 1982 | JP.
| |
271992 | Nov., 1987 | JP | 415/55.
|
Primary Examiner: Kwon; John T.
Attorney, Agent or Firm: Browdy & Neimark
Claims
What is claimed:
1. A rotary suction and blowing machine comprising:
an impeller including substantially rectangular blades set parallel to a
rotation axis of the impeller;
a body, in which the impeller is rotatably mounted for rotation about the
axis thereof, having an annular conduit therein and a delivery mouth and
an intake mouth each communicating with the annular conduit;
the annular conduit including a first tract and a second tract;
the second tract defining, parallel to the rotation axis, a rectangular
outline;
the first tract further comprising two communicating semichannels and
defining, parallel to the rotation axis, an outer portion of an
intersecting-circle outline including two generally circular portions
forming therebetween a projecting portion terminating in a first point;
the impeller, exclusive of the blades, defining parallel to the rotation
axis a complementary inner portion of the intersecting-circle outline
including a second projecting portion terminating in a second point;
the first point and the second point being separated by a gap.
2. The machine according to claim 1, wherein the point is situated at a
half-way point of the first tract.
Description
BACKGROUND OF THE INVENTION
Reference is made in particular to a machine with lateral channel or air
ring comprising an impeller provided with blades and closed in a body
affording an annular conduit in which the impeller blades rotate. The
annular conduit exhibits a suction mouth and a delivery mouth through
which mouths a fluid can enter and exit the machine.
The annular conduit exhibits a first tract which, following the advancement
direction of the blades in the conduit, extends from the intake mouth to
the delivery mouth, and a second tract which goes from the delivery mouth
to the intake mouth. The first tract has a transversal passage section
which is greater than that of the second tract.
More precisely, each blade completely crosses the second tract, clearing
the internal walls by only a very small distance; a distance which is
preferably the smallest possible which is compatible, obviously, with
degrees of friction permissible. A free space is left between the internal
walls of the first tract and the blades, which free space is considerably
greater and in which fluid turbulence can occur.
During functioning of the machine, the dynamic action of the blades
generates a fluid current in the first tract of the annular conduit which
is directed from the intake mouth towards the delivery mouth.
The conformation of the annular conduit, and in particular the presence of
the abovementioned free space between the blades and the internal walls of
the first tract of the annular conduit is necessary so that the motion of
the blades causes an effective fluid current from the intake mouth to the
delivery mouth.
The prior art teaches machines in which the first tract of the annular
channel is divided into two symmetrical semichannels separated one from
the other by radial walls arranged between one and a next blade, which
generate a sort of dividing wall which in the first tract gives rise to a
dragging seal on a corresponding dividing wall made at the peripheral
surface of the same annular channel. Such realizations have the defect
that the air flows generated in the two semichannels do not allow for the
machine to self-balance.
In other realizations the blades rotate freely internally of the wide
second channel without the presence of dividing walls physically dividing
the annular channel into two semichannels, so that there is free
communication between the two sides of the blade crown. A machine of this
type is described in Italian patent IT 1225173 by the present applicant.
In such a machine there is greater self-balance, due to the fact that the
two flows of air generated in the two semichannels can freely interact.
SUMMARY OF THE INVENTION
The main aim of the present invention is to provide a machine of the same
type as the one described above, which is however more productive. A
further aim of the present invention is to realize a machine in which the
self-balance is still further improved.
An advantage of the invention is that it achieves the above-mentioned aims
while remaining constructionally simple and economic.
A further advantage is that the machine of the invention has a high
performance both in terms of flow rate and head.
A still further advantage is the low generation of noise during operation.
These aims and advantages and others besides are all achieved by the
machine of the invention, as it is characterized in the following claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Further characteristics and advantages of the invention will better emerge
from the detailed description that follows, of a preferred embodiment of
the machine, illustrated in the accompanying drawings purely in the form
of a non-limiting example, in which:
FIG. 1 is a vertical-elevation frontal view of the machine;
FIG. 2 is a section made according to line II--II of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to the figures, 1 denotes a rotary suction and blowing
machine in its entirety.
The machine 1 is of the two-stage type, comprising two series-arranged
single stage motors.
Each stage of the machine 1 comprises an impeller 2 provided with blades 3,
the whole being closed inside a body 4 affording an annular conduit 5
internally of which the blades 3 of the impeller 2 rotate. The rotation
direction of the blades 3 is indicated by an arrow 6.
The impeller 2 comprises a central hub 7 for connection with a rotating
shaft, not illustrated, having a rotation axis indicated by x--x.
Each blade 3 exhibits a peripheral edge 30, parallel to the axis x--x, and
two opposite lateral edges 31 which develop on planes which are normal to
axis x--x.
The annular conduit 5 comprises a first tract 50 at one end of which which
an intake mouth 8 is situated, while at another end thereof is located a
delivery mouth (not illustrated). In FIGS. 2, 8 denotes the intake mouth
of the first stage and 9 the delivery mouth of the second stage. The
transversal section of the first tract 50 of the annular conduit 5 is
practically constant over its whole length.
The annular conduit 5 further comprises a second tract 51 which, with
reference to the direction of motion of the blades in the annular conduit
5, extends from the delivery mouth 8 to the intake mouth (not
illustrated).
The second tract 51 exhibits a transversal passage section (i.e., parallel
to the rotation axis x--x) below that of the first tract 50 which is of
rectangular outline, as shown in the drawing; further, the first tract 50
is considerably longer than the second tract 51.
The straight transversal passage section of the second tract 51 of the
annular conduit 5 is, by shape and size, more or less the same or at most
a little longer than the transversal section of the blade 3 crown, so that
the peripheral edge 30 and the lateral edges 31 of each blade just breast
the internal walls of the second tract 51 during rotation.
Contrarily, in the first tract 50 there is a free space between the
internal walls of the annular conduit 5 and the peripheral and lateral
edges of each blade 3. As is clearly visible in FIG. 2, the first tract 50
defines, parallel to the rotation axis x--x, the outer portion of an
outline formed of two intersecting circles. The intersection-circle
outline's two generally circular portions include the projecting element
or portion 10 terminating in a point. The impeller 2 (exclusive of the
blades 3) defines a complementary inner portion of the intersecting-circle
outline. As seen in FIG. 2, the cross-hatched rim of the impeller 2 has a
second projecting element terminating in a second point, which is radially
separated from the first point by a gap.
This free space is necessary in order to obtain good aspirated or blown
fluid head from the intake mouth 8 to the delivery mouth. In the first
tract 50 therefore two communicating semichannels are generated, the
presence of which permits the machine to self-balance to a considerable
degree. All of the above refers to a single stage. A skilled person would
intuit how two single machines would be connected in series to obtain the
two-stage machine 1 illustrated in the accompanying figures. Briefly, the
delivery of the first stage would be placed in communication with the
intake of the second stage.
The characteristics described heretofore are common to the prior art and
the present machine.
In the present invention, a projecting element 10 is associated to each
stage of the machine 1, and is located solidly to a wall peripherally
delimiting the first tract 50 of the annluar conduit 5, and is facing the
peripheral walls 30 of the blades 3. This projecting element 10 projects
internalwise of the first tract of annular conduit 5 and is shaped and
arranged such as to define two concave surfaces 11 separated one from the
other by the projecting element itself and extending mutually parallel
along the entire length of the first tract 50 of the annular conduit 5.
The principal function of the projecting element 10 is to deflect the
fluid, which is moved by the blades 3 turbulently in the first tract 50 of
the annular conduit 5, such as to generate a situation in which a double
vortex fluid flow is created which approximately follows the direction of
the two concave surfaces 11.
This double vortex is superposed on the component of the fluid flow
direction responsible for the formation of a fluid head, that is the
component flowing along the axis of the annular conduit 5. The double
vortex 5 caused by the presence of the projecting element 10 is
responsible for the considerable improvement in performance noted at every
stage of the machine 1 with respect to all other machines in the prior
art.
The projecting element 10 preferably exhibits a transversal section in the
shape of a cusp (as can be seen clearly in FIG. 2) with connected sides,
and terminates in a point situated at a very short distance from the
peripheral edges 30 of the blades 3. During the blades' 3 rotation, the
edges 30 breast the point of the cusp. The projecting element 10 is
preferably situated at the halfway point of the annular conduit 5.
The projecting element can be made in a single piece with the wall of the
first tract 50 of the annular conduit 5 which is facing the peripheral
edges of the blades 3. This is the case with the left stage in FIG. 2.
Alternatively the projecting element 10 can be made separately and fixed on
to the wall. This is the case in the right stage illustrated in FIG. 2,
where on the wall peripherally delimiting the first tract 50 of the
annular conduit 5 and facing the peripheral edges 30 of the blades 3 there
is an annular niche 12 housing the projecting element 10.
The second embodiment of the machine 1, with the projecting element 10
housed in the annular niche 12, is easily applicable also to known
machines. The niche 12 could be sunk in the peripheral wall of the annular
channel of a known machine and the projecting element 10 (separately made)
inserted therein. The projecting element 10 might advantageously be made
in two parts to ease its insertion into the niche 12, and might be fixed
therein by friction force.
The projecting element 10 is conformed and arranged such that once inserted
in the niche 12 its concave surfaces 11 are continuously disposed thereto,
contributing considerably to the good functioning of the machine. Making a
niche 12 contributes to obtaining smooth and continuous concave surfaces
11 in cases where the projecting element 10 is constructed separately and
subsequently located on the conduit 5 wall.
In all illustrated embodiments the presence of the projecting element 10
contributes to accentuating the subdivision of the first channel tract 50
into two symmetrical semichannels having the important characteristic of
being in mutual communication. This enables regular developing of the air
flows which, thanks to the possibility of free interaction, allow for
excellent self-balancing of the machine as well as obtaining high
performance.
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